Picard made himself the face of the Romulan rescue operations. He made grandiose promises that he said would be delivered on and weren't. Yes it wasn't entirely his fault they weren't, but people like to have someone they can blame their misfortunes on, and he did make those promises. Then Picard did make a conscious choice to run away instead of continue to keep fighting or even admit he couldn't live up to his promises, so that hatred festered. And he and we can see this laid out in the episode.
It's not an accident that aphorisms like "A promise is a trap", "You couldn't save everyone, so you chose to save no one," and "I allowed the perfect to be the enemy of the good," inform us what is going on here. I get it that you don't care for this line of storytelling, but to anyone watching it's pretty clear what it going on and it's not an unrealistic turn of events and it doesn't turn Picard into a "Moral Mary Sue" because by letting his pride and self-righteousness prevent himself from facing the music and carry one fighting the good fight, he fucked up.